In the separation of materials of varying densities, it is well known to impart centripetal force to the material so that the resulting acceleration causes a density related distribution of material. For example, cyclonic collectors have been employed for many years for the removal of solid particles from gaseous streams. A cyclonic collector is a stationary device with no moving parts which converts the entering gas stream to a vortex. Centripetal force acts on the particles in the gas stream causing them to migrate to the outside wall where they are collected by inertial impingement. Since the force developed can be many times that of the force due to gravity, very small particles can be separated out of the gas stream. U.S. Pat. No. 325,521 discloses a very early cyclone design for the separation of dust from air. Cyclonic collectors are frequently used in the control of air pollution. Various conventional cyclonic collector designs are described in Kirk-Othmer, ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, Third Edition, John Wiley & Sons, 1978, Vol. 1, pages 667-673, incorporated by reference for the disclosure of such details.
As can be appreciated, cyclones and modified cyclonic collectors can be used to remove entrained liquids from a gas stream. Even the crudest device can capture liquid droplets larger than 100 micrometers if care is taken to prevent liquid reentrainment. Wet cyclones are described in some detail by Stern, Caplan and Bush in CYCLONE DUST COLLECTORS, American Petroleum Institute, New York, N.Y., 1955. Gas-liquid cyclones are also discussed in Rousseau, HANDBOOK OF SEPARATION PROCESS TECHNOLOGY, John Wiley & Sons, 1987, pages 132-137, incorporated herein by reference.
Fluid cyclones and hydrocyclones have found acceptance within the paper-making and metallurgical industries and elsewhere. The most common type of hydrocyclone utilizes a straight conical design wherein fluid enters through a tangential inlet into a short cylindrical section. A vortex is created in the cylindrical section and in a conical section located directly below as the fluid spirals in a path moving downward and inward, then upward in a helical path to an exit pipe co-axial with the cylindrical section. As with the dry cyclone, the centripetal acceleration imparted by the rapid rotation of the fluid causes dense particles to be forced outward to the outer wall surfaces of the cylindrical and conical sections. The dense particles are transported in the slower moving boundary layer downward towards the apex of the conical section where an exit orifice is therein provided. The high centripetal force near the center creates a liquid-free zone referred to by those skilled in the art as a vortex cone. In the conical cyclone, this core is filled with air and a back pressure at the exit of the hydrocyclone is required to prevent air from being sucked in.
Related patents include U.S. Pat. No. 3,862,714, which discloses an apparatus for the vortical separation of fluid material. The apparatus includes an annular zone between two rotating cylindrical surfaces wherein the fluid material is introduced into this zone to form a forced vortex having an axial component of motion of predetermined profile. Centripetal acceleration causes a distribution of the fluid material with the more dense material located further from the axis.
U.S. Pat. No. 4,251,368 discloses a cyclone separator having a generally cylindrical first portion with a plurality of substantially equally spaced directed feeds. Adjacent to and coaxial with the first portion is a generally cylindrical second portion open at its far end. The first portion has an axial overflow outlet opposite the second portion. Optionally, a flow-smoothing taper is provided between the inlet portion and the separating portion. The apparatus disclosed finds utility in the removal of oil from water in oil-rig drilling and aboard ships involved in the sea transport of oil.
U.S. Pat. No. 4,389,307 is directed to a form of fluid cyclone in which the velocity energy of the exit fluid is converted into exit pressure permitting the device disclosed to discharge at atmospheric pressure or higher while a vacuum exists in the central core of the vortex.
U.S. Pat. No. 4,844,817 discloses a system for the separation of oil from oily water where the oily water is available at relatively low pressure insufficient to drive a hydrocyclone separator. A particular combination of pumps and hydrocyclones is disclosed which is said to be effective under low pressure situations.
Despite these advances in the art, there exists a need for an improved material extraction nozzle capable of effectively separating materials of different densities, particularly gas-liquid mixtures.